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<br /> <br />Page 1 of 3 <br /> <br />Joint Development Authority <br /> TCAAP Redevelopment Project <br /> <br />DATE: October 9, 2017 <br /> <br />TO: Joint Development Authority Board of Commissioners <br /> <br />FROM: <br /> <br />CC: <br />Beth Engum, Ramsey County Project Manager <br />Josh Olson, JDA Administrative Director <br /> <br />William Joynes, JDA Administrator Director Josh Olson <br />Lee Mehrkens, Chief Financial Officer, Ramsey County <br />Louis Jambois, TCAAP Project Negotiator, Ramsey County <br /> <br />SUBJECT: TGRS Optimization Study <br /> <br />This memorandum has been prepared at the request of the Joint Development Authority at their <br />meeting on September 20, 2017 to update the Authority on the status of the TGRS Optimization Study <br />process. <br /> <br />The TCAAP Groundwater Remediation System (TGRS) began operating in 1987, largely within the 427- <br />acre Rice Creek Commons (RCC) redevelopment site, to treat contaminated groundwater resulting from <br />the manufacturing of munitions dating back to the 1940s. The TGRS was installed by and is the operating <br />responsibility of the U.S. Army. The TGRS removes volatile organic compounds (VOCs) primarily <br />trichloroethylene (TCE) from the groundwater. TCE is a chemical compound used as an industrial <br />solvent Groundwater is extracted from the aquifer via 11 active wells and sent to the water treatment <br />plant on the east side of the site via an underground network of pressurized pipes. TCE is removed from <br />the water via an air stripping process and the clean water is pumped underground to a gravel pit located <br />northeast of the site on Arden Hills Army Training Site (AHATS) where treated water infiltrates back into <br />the aquifer. <br /> <br />Since it was installed, the TGRS has made significant strides towards cleaning up the groundwater, <br />removing hundreds of pounds of VOCs over the last 20+ years. The level of VOCs in the groundwater, as <br />measured from monitoring wells onsite and downstream, is less than when the system began pumping. <br />Variability exists in the level of VOCs still detected depending on which monitoring well is tested and <br />whether the water is being pumped from the bedrock or overlying sands, among other possible reasons. <br />This raises questions relative to the Army’s obligation to regulators in removing VOC contaminants from <br />the groundwater: <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />MEMORANDUM